Drug Discov Ther. 2009;3(4):176-180.

Microspheres of tramadol hydrochloride compressed along with a loading dose: A modified approach for sustaining release.

Gonjari ID, Hosmani AH, Karmarkar AB, Kadam SB, Godage AS, Khade TS

The purpose of this research was to study mucoadhesive microspheres of tramadol hydrochloride compressed into tablet along with a loading dose. Microspheres containing tramadol hydrochloride were prepared by employing sodium alginate in combination with a mucoadhesive polymer, i.e., Carbopol 971P. An orifice-ionic gelation method was used to prepare the microspheres. A 3² factorial design was used to investigate the combined effect of two independent formulation variables in the preparation of microspheres. The concentration of sodium alginate (X₁) and carbopol 971P (X₂) were selected as independent variables. Nine batches were used in the experimental design and evaluated for swelling index, mucoadhesion, and drug entrapment efficiency. A surface plot is presented to graphically represent the effect of the independent variables on the evaluation parameters. The best batch exhibited drug entrapment efficiency of 70.12%, swelling index of 2.3 and mucoadhesion of 95.42%. Microspheres showing maximum drug entrapment were compressed with the loading dose and subjected to in vitro dissolution studies. Drug release from tablets was found to follow a matrix model. Initial burst release from these tablets indicated the release of the loading dose and then a sustained effect over the time. This modified approach to formulation of tablets was found to be effective in sustaining drug release.

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